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Spec Dinosauria: Rhynchoraptoria
HISTORY Many aspects of the Spec-Australian biota are unique and bizarre, none more so than the 30 species of rhynchoraptors, carnivorous ornithopods that dominate the large predator guilds of this continent. They are amongst the most highly specialized ornithischians in the world and are the first non-theropodian big-game land predators to have evolved since at least the Late Triassic. Their ancestry can be traced to small, basal euornithopods of the same stock that produced the euclasaurs and viriosaurs. Many small, normally herbivorous ornithopods even today will often take insects and smaller vertebrate animals and in the Late Paleocene, one family became increasingly adapted for omnivory. The poorly understood Eocene-Oligocene Extinction Event cleared out Australia's top predators (abelisaurids and deinonychosaurs). In the ensuing ecological vacuum, two dinosaurian lineages - the early rhynchoraptors and the ancestors of the cedunasaurs -competed for supremacy in the large predator guilds, a competition in which the rhynchoraptors were ultimately successful. BIOLOGY The skull of a rhynchoraptor immediately betrays both its predatory nature and its ornithopod heritage. The predentary bone has become a long, curved stabbing structure. The front pairs of teeth have become similarly adapted for stabbing. The upper pair (the sole remaining premaxillary teeth) slide around the narrow predentary when the mouth is closed whilst the bottom pair (the first two dentary teeth) slot into a pit just behind the premaxilla. Unlike theropods, the rhynchoraptors are precision biters using their specially adapted dentition to crush or pierce the jugular or some other vital structure on their victim. The foreclaws have become long and curved to aid in securing the victim. Smaller rhychoraptors run on two legs whilst the larger species are facultative quadrupeds. An odd feature: the smaller forms are primarily egg-layers whilst the large species are viviparous. Recent DNA analyses reveal that some purported species are actually complexes of similar forms, in particular, so-called Papuan subspecies of Australian diamondbacks and jagdpanthers are separate species in their own right. Additionally recent surveys of Melanesia have uncovered many previously unknown forms. In fact, if anything the rhynchoraptor stranglehold on the predatory guilds on these islands is even more complete than in Australia, although diversity tapers off west of Wallace's line. DASPLETODONTIDAE The Anklebiter With their bipedal postures and protruding fangs, daspletodontids---the aptly-named anklebiters---bear a strong (if entirely superficial) resemblance to the ancient heterodontosaurs. These little predators are, however, rynchoraptors, only distantly related to the heterodontosaurs. Uncommon on mainland Australia, anklebiters are the dominant (often the only) predators of the Melanesian islands. Many species are found on Papua as well (although there they play second fiddle to their larger cousins). The smallest rhynchoraptor, the anklebiter (Daspletodon nanus), is an agile hunter of mammals and small dinosaurs on the forest floor. Understandably, this form was initially described as a possible heterodontosaur when it was first discovered. guards her offspring from a marauding anklebiter.]] VENATORODNTIDAE The Island Runt It was commonly believed that alvarezasaurs were the only species of dinosaurs, as well as the birds, to inhabit the neighboring island of New Zealand. However, the is an exception to the rule in the form of the Island Runt (Venatorodon horrificus). How they got there is still a mystery science is trying to solve. As of now very little is known about their behavior, although they have been obserbved feeding on eggs, birds, reptiles and small mammals. When it was first discovered, it was thought to be new species of ankle-biter. However, closely examination revealed that it was not only a new species, but its own separate genus. RHYNCHORAPTORIDAE All large rhynchoraptors are ambush predators that subdue their prey with their forelimbs before dealing a lethal precision bite. They started out as small bipeds (ie. anklebiter) - however as they began to target larger, more dangerous prey their forelimbs became increasingly large and well-muscled while their frontal osteology became robust and reinforced to hand the rough-and-tumble activity (they are a lot more solidly built than a comparable sized theropod). Eventually the larger rhynchoraptors (formally Rhynchoraptoridae) were too front heavy for practical bipedalism. The Jagdpanther This majestic predator, the jagdpanther (Rhynchoraptor diabolus), is found throughout the continent from semi-desert to rainforest-edge. It is largely nocturnal and hunts in small packs, often tackling animals far larger than themselves but will also run down smaller prey. The Greater Diamondhide The greater diamondhide (Rhynchoraptor regius) is the principal predators of the forests and plains of southern Australia. Typical rhychoraptors, diamondhides hunt in packs, running their prey to exhaustion before wrestling it to the ground and dispatching it with a bite to the throat. The Lesser Diamondhide In Australia, species generally grow smaller as one progresses northwards, and the lesser diamondhide (Rhynchoraptor minimus) is no exception. This 1.8 meter-long predator lives in Australia's northeastern forests and plains where it eats mammals, reptiles, and smaller dinosaurs (including small birds) and other rhyncoraptors, most notably the blacktip. The Blacktip The blacktip is a fox-sized rhyncoraptor (Carnornithopodia ferox) that lives in northwestern and southwestern Australia. It is considered to be the smallest member of the main land rhynchoraptorids. It preys on a wide variety of creatures including birds, mammals, reptiles, amphibians insects, and carrion. Interestingly enough, just like the foxes back on home earth, it will dig burrows in the Australian soil; most likely to use it as refuge to hide from large predators, most notably the larger rhynchoraptors, and as a place to incubate their eggs. The Strumtiger The largest terrestrial carnivore on the continent growing up to lengths of 20 feet long, the strumtiger (Sauropanthera rex) is a solitary hunter that stakes out a huge territory in a wide variety of habitats. It primarily hunts large, slow moving herbivores but also does a significant amount of scavenging. For it's size, the strumtiger is surprisingly agile and swims well. The Sturmtiger and Jagdpanther seem to share a deep hatred for one another and both species will go to great lengths to violently remove the other from their respective territories. One documented sighting involved a pack of 7 jagdpanthers that attacked a young male sturmtiger, eventually tearing him to pieces after losing 3 of their number. RECENTLY DISCOVERED RHYNCHORAPTORIDS The Winkle Growing up to lengths of 9 feet long, the winkle, (Rhynchoraptoroides gracilis), is one of the least studied members of the Rhynchoraptor family. However, we do know a few behaviors based on the very few observations that were conducted. We know that this species prefers to live in coastal environments scavenging on anything washed up from the sea, ripping open carcasses with long talons or preying the local fish and sea birds that inhabit the area. Surprisingly, these appear to be the least hostile members of the Rhynchoraptorids. Despite is appearance of having no noticeable fangs, its still a carnivore by nature. The Blitzkrieg Growing up to lengths of 7 feet long and weighing up to 500 pounds, the Blitzkrieg (Acinonyxosaurus velox) is a recently discovered species of Rhynchoraptor who gets its well deserved name from its observed hunting strategy and speed, caplable of running up to speeds of 30-35 miles per hour, very similar to the Cheetahs of home earth. However, unlike the cheetah, this species a more social animal, usually hunts in packs consisting of 5 members usually lead by an alpha female. Running down smaller prey or attacking larger prey in groups. Interestingly, in times of scarce food, the Blitzkreg has been known display behaviors of having an omnivorous diet, eating tree bark, desert plants and carrion. The Nashorn This small species of Rhynchoraptor known as the nashorn (Nanorhynchoraptor flanneryi) can be found roaming the rainforests of central Australia, often leading a solitary life and growing up to lengths of 3.2 feet long. One of the most noticeable features is its robust nose, scientists have debated its purpose, but the most likely conclusion is that is it used to track down smaller prey thanks to an incredible sense of smell. The First Rhynchoraptorid That Wasn't: New Fossil Material Found of Gryphorhynchus robustus New fossils unearthed from Late Oligocene deposits at Spec Riversleigh have proven Gryphorynchus, once thought to have been the first rhynchoraptoran predator, to be something else instead.Until now Gryphorhynchus was known from an incomplete skull and some fragmentary limb and pelvic material. Based on the fossils scientists had reconstructed the animal as a sleek and swift predator not unlike the smallest modern rhynchoraptors. It was thought to be closely related to the common ancestor of rhynchoraptors. The newly found Gryphorhynchus skeleton, nicknamed "Greg", has proven these reconstructions flawed. The new animal that belongs to a new species, Gryphorhynchus robustus, that was clearly closely related to the earlier fossils. In fact it is possible that the bones found earlier belonged to a juvenile G. robustus. "In life Greg was a big and bulky beast and probably not much of a runner. It's more likely that he was an omnivorous scavenger," said Specpaleontologist Kim Xu, who was involved in the excavation of the animal. Though the otherwise nearly complete skeleton is missing nearly all of the tail, it has become clear that Gryphorynchus was too different from Rhynchoraptors to be a closely related to them. "It likely now that the antarctornithopods that gave rise to rhynchoraptors experimented with omnivory and maybe even carnivory several times," Xu said. "This means the earliest rhynchoraptoran remains are now from the Miocene," said professor Brian Chou, who has been studying fossil rhynchoraptors for years. "But that doesn't necessarily mean they aren't there. We just haven't found them yet," he added. from 'Spexploration Weekly, November 2003 Issue. ' ---- - Brian Choo and Daniel Bensen ---- ,=Daspletodontidae=Daspletodon nanus (Anklebiter) Venatorodontidae=Venatorodon horrificus (Island Runt) =Rhynchoraptoria=| | ,=R. diabolus (Jagdpanther) | ,=Rhynchoraptor=| | ,=| | ,=R. regius (Greater diamondhide) | | | `=| | | | `=R. minimus (Lesser diamondhide) | | | | | `=Carnornithopodia ferox (Blacktip) `=Rhynchoraptoridae=| `=Sauropanthera rex (Sturmtiger) Rhynchoraptoroides gracilis (Winkle) Acinonyxosaurus velox (Blitzkrieg) Nanorhynchoraptor flanneryi (Nashorn) Gryphorhynchus robustus (Greg)† ---- Category:Spec Dinosauria Category:Animals Category:Alternate History Animals Category:Dinosaurs Category:Alternative timelines Category:Alternative evolution Category:Australia Category:Ornithischia Category:Ornithopods Category:New Guinea Category:Cerapods Category:Neornithischia Category:Genasaurs Category:Carnivores Category:Amniotes Category:Craniates Category:Sauropsids